U.S. patent number 4,441,563 [Application Number 06/317,151] was granted by the patent office on 1984-04-10 for tool collet and control means.
This patent grant is currently assigned to Black & Decker Inc.. Invention is credited to Richard E. Walton, II.
United States Patent |
4,441,563 |
Walton, II |
April 10, 1984 |
Tool collet and control means
Abstract
A power tool, such as a surgical drill, has a tool element
retained in a collet coupled to the output spindle of the tool.
Resilient member constantly maintains the collet in its closed
position. Upon rotation of the spindle in a reverse direction,
opposite to its normal driving direction, a cam is actuated to open
the collet against the force of the resilient member, thereby
facilitating removal of the tool element from the collet.
Preferably, the tool is of the cordless type and has a reversible
electric motor controlled by a pair of triggers mounted on the
pistol-grip handle for the tool. The triggers are conveniently
disposed adjacent to each other and are easily distinguishable from
one another, thereby providing for a convenient one-hand operation
of the tool.
Inventors: |
Walton, II; Richard E.
(Fallston, MD) |
Assignee: |
Black & Decker Inc.
(Newark, DE)
|
Family
ID: |
23232336 |
Appl.
No.: |
06/317,151 |
Filed: |
November 2, 1981 |
Current U.S.
Class: |
173/213; 173/167;
606/104 |
Current CPC
Class: |
A61B
17/162 (20130101); B23B 45/001 (20130101); B23B
31/201 (20130101); A61B 17/1626 (20130101) |
Current International
Class: |
A61B
17/16 (20060101); B23B 45/00 (20060101); B23B
31/20 (20060101); A61B 017/18 () |
Field of
Search: |
;173/163,167,46
;279/30,51,75 ;128/92EB,92EC,303,305 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kazenske; E. R.
Assistant Examiner: Fridie, Jr.; W.
Attorney, Agent or Firm: Sherer; R. B. Weinstein; Harold
Yocum; Charles E.
Claims
I claim:
1. In a tool having a housing with a spindle drivingly connected to
a motor and journaled in the housing for rotation in a forward and
reverse direction, respectively, the tool further having collet
means for retaining a tool element driven by the spindle, and the
collet means having an open position and a closed position,
respectively, the improvement which comprises, in combination,
frictional means for constantly urging the collet means in its
closed position, the collet means remaining closed in the forward
direction of rotation of the spindle corresponding to the driving
mode of operation of the tool, and cam means, responsive to the
motor rotating the spindle in the reverse direction, for moving the
collet means from its closed position into its open position
against the force of the frictional means, the cam means including
a cam track and an antifriction cam follower operatively associated
with the cam track, the antifriction cam follower being out of
operative engagement with the cam track in the forward direction of
rotation, and operatively engaging the cam track in the reverse
direction of rotation, the cam means thereby being an overrunning
clutch in the forward direction and a slip clutch in the reverse
direction of rotation of the spindle.
2. In a portable tool having a housing with a driving spindle
journaled therein for rotation in a forward and reverse direction,
respectively, the tool further having collet means having an open
and a closed position for retaining a driven tool element therein,
the improvement which comprises, in combination, means including a
resilient member for constantly urging the collet means in its
closed position, the collet means remaining closed in the forward
direction of rotation of the spindle corresponding to the driving
mode of operation of the tool, and cam means responsive to reverse
rotation of the spindle to move the collet means from its closed
position into its open position against the bias force of the
resilient member, thereby facilitating removal of the tool element
from the collet means, the cam means functioning as an overrunning
clutch in the forward direction, and the cam means including a cam
member movable axially relative to the spindle, a stationary thrust
ring in the housing, a cam track formed on the cam member, a ball
loosely disposed axially between the thrust ring and the cam track
in the forward direction of spindle rotation corresponding to the
closed position of the collet means, and wherein the cam track
engages the ball in the reverse direction of spindle rotation,
thereby moving the cam member forwardly in the open position of the
collet means.
3. The improvement of claim 2, wherein a shoulder member is carried
by the spindle forwardly of the cam member, and wherein the
resilient means comprises a compression spring disposed
concentrically about the spindle and seated axially between the cam
member and the shoulder member.
4. The combination of claim 2, further including a nose housing
concentrically about the collet means.
5. In a portable tool having a housing with a driving spindle
journaled therein for rotation in a forward and reverse direction,
respectively, the tool further having collet means having an open
and a closed position for retaining a driven tool element therein,
the improvement which comprises, in combination, means including a
resilient member for constantly urging the collet means in its
closed position, the collet means remaining closed in the forward
direction of rotation of the spindle corresponding to the driving
mode of operation of the tool, a nose housing located
concentrically about the collet means, the collet means including a
collet member having a rearward portion and a radially-enlarged
slotted forward portion to receive the tool element, the forward
portion projecting forwardly of the spindle and being seated
between the spindle and the nose housing, and cam means responsive
to reverse rotation of the spindle to move the collet means from
its closed position into its open position against the bias force
of the resilient member, thereby facilitating removal of the tool
element from the collet means, the cam means functioning as an
overrunning clutch in the forward direction.
6. The improvement of claim 5, wherein the collet member has a
rearward portion received within the bore of the spindle.
7. The improvement of claim 14, wherein the rearward portion of the
collet member is secured to the spindle for rotation in unison.
8. The combination of claim 5, further including complementary
tapers formed on the nose housing and the forward portion of the
collet member, respectively, and on the spindle and the collet
member, respectively.
9. The improvement of claim 5, wherein the nose housing has a
rearward portion secured to the cam member, whereby the spring
constantly urges the cam and hence the nose housing rearwardly of
the spindle, thereby holding the nose housing firmly against the
collet member to maintain the collet member in its closed
position.
10. In a tool, the combination of a spindle journaled for rotation
in the tool, the spindle having forward and reverse directions of
rotation, respectively, a slotted collet mounted forwardly of the
spindle, the collet having an open position and a closed position
for retaining a driven tool element therein, a nose housing
concentrically around the collet and spindle, the nose housing
having a forward portion and a cylindrical rearward portion, the
forward portion having a tapered internal annular surface, the
collet having a complementary tapered external annular surface for
seating the collet within the nose housing, a cam secured to the
rearward portion of the nose housing, the cam and nose housing
being free to move axially of the spindle, a shoulder on the
spindle, a compression spring disposed concentrically about the
spindle and seated axially between the cam and the shoulder,
thereby constantly urging the cam and nose housing rearwardly of
the spindle, and thereby firmly seating the collet within the nose
housing to maintain the collet in its closed position during
forward rotation of the spindle, a stationary thrust ring in the
tool concentrically of the spindle and rearwardly of the cam, the
cam having a cam track formed therein, and a cam follower between
the cam and the thrust ring, whereby upon reverse rotation of the
spindle, the cam track engages the cam follower to move the cam and
nose housing forwardly of the spindle, thereby separating the nose
housing from the collet, and thereby opening the collet to
facilitate removal of the tool element therefrom.
11. The combination of claim 10, wherein the cam follower is out of
engagement with the cam track in the forward direction of rotation
of the spindle, corresponding to the normal driving mode of
operation of the tool, whereby the cam functions as an overrunning
clutch during operation of the tool.
12. The combination of claim 10, wherein the cam follower and cam
track function as a slip clutch in the reverse direction of
rotation of the spindle.
13. The combination of claim 10, further including an outer ring
concentrically about the cam to radially retain the cam
follower.
14. The combination of claim 10, wherein the cam follower comprises
a ball.
15. The combination of claim 10, wherein the cam track has a helix
angle of less than 7 degrees.
16. The combination of any of claims 14 or 15, wherein the cam
track terminates on its high side in a flat ledge for positioning
the cam follower thereon upon reversal of the spindle rotation.
17. The combination of claim 10, wherein the tool comprises a
portable electric tool having a housing with a motor therein for
driving the spindle.
18. The combination of claim 17, wherein the portable electric tool
comprises a cordless drill.
19. The combination of claim 18, wherein the tool comprises a
surgical drill having a cannulated spindle provided with a through
bore, and wherein the tool element comprises a K-wire received
within the bore of the cannulated spindle.
20. The combination of claim 10, wherein the tool comprises a
portable pneumatic tool.
21. The combination of claim 10, wherein the tool comprises a
portable hobbyist tool powered by a flexible cable.
22. The combination of claim 10, wherein the tool comprises a
manually-operable device.
23. In a surgical drill of the type having a cannulated driving
spindle provided with a longitudinal through bore for receiving a
K-wire or the like, means for retaining the wire with respect to
the spindle for conjoint rotation in unison, said means comprising,
in combination, a nose housing enclosing the spindle and having an
internally-tapered forward portion and a cylindrical rearward
portion, a driven collet having a slotted externally-tapered
portion projecting forwardly of the spindle and seated within the
complementary internally-tapered forward portion of the nose
housing, the collet having an open position and a closed position
for retaining the K-wire therein, a shoulder member mounted on the
spindle, a cam freely mounted on the spindle rearwardly of the
shoulder member, the cam being secured to the rearward cylindrical
portion of the nose housing, a stationary thrust ring retained in
the housing rearwardly of the cam, the cam having a rearward
portion formed with a cam track, a ball between the cam track and
the thrust ring, means for retaining the ball radially of the
spindle, resilient means between the cam and the shoulder member,
constantly urging the cam and hence the nose housing in a direction
rearwardly of the spindle, thereby closing the collet and securing
the K-wire therein, the ball having a loose engagement in the cam
track in one direction of rotation of the spindle corresponding to
the driving mode of operation of the tool, and the cam track
engaging the ball in the opposite direction of rotation of the
spindle to move the cam and hence the nose housing axially along
the spindle and forwardly of the drill and against the force of the
resilient means, thereby separating the complementary tapered
portions of the collet and nose housing, respectively, and thereby
opening the collet to facilitate release of the K-wire
therefrom.
24. In a power tool having a housing and a spindle journaled
therein for rotation in forward and reverse directions,
respectively, the tool further having a collet with a tool element
retained therein, the subcombination of cam means including a cam
member, a cam track formed on the cam member, and a cam follower,
the cam follower being disengaged from the cam track in the forward
direction of spindle rotation, the cam means thereby functioning as
an overrunning clutch in the forward direction, and the cam track
engaging the cam follower in the reverse direction of spindle
rotation to move the cam member within the housing to open the
collet to facilitate removal of the tool element therefrom, the cam
means thereby functioning as a slip clutch in the reverse direction
of spindle rotation.
25. The subcombination of claim 24, wherein the cam follower
comprises a ball, and wherein the cam track has a helix angle of
less than 7 degrees.
26. In a power tool having a housing provided with a pistol-grip
handle depending therefrom, a motor in the housing, and a spindle
journaled in the housing and driven by the motor, the combination
of collet means for a tool element driven by the spindle, the
collet means having an open position and further having a closed
position for securing a tool element therein, an "open" trigger and
a "drive" trigger mounted in the pistol-grip handle and projecting
forwardly therefrom, the triggers being disposed substantially
adjacent to each other and being readily distinguishable from one
another by the operator, means responsive to engagement of the
"open" trigger for moving the collet means into its open position,
thereby to facilitate the insertion of a tool element therein, and
means responsive to the subsequent engagement of the "drive"
trigger for moving the collet means into its closed position,
thereby retaining the tool element therein, the collet being held
in its closed position regardless of the continuous engagement of
the "drive" trigger, and the collet means being subsequently moved
back into its open position only upon the engagement of the "open"
trigger, thereby facilitating release of the tool element from the
collet means, whereby the operator has immediate and total control
without looking at the tool itself and without requiring a shifting
of the operator's hand relative to the pistol-grip handle.
27. In a power tool having a housing provided with a pistol-grip
handle depending therefrom, a motor in the housing, and a spindle
journaled in the housing and driven by the motor, the combination
of collet means for a tool element driven by the spindle, the
collet means having an open position and further having a closed
position for securing a tool element therein, an "open" trigger and
a "drive" trigger disposed substantially adjacent to each other,
the triggers being mounted in the pistol-grip handle and projecting
forwardly therefrom, the "drive" trigger being larger than the
"open" trigger and having a forward face formed with an arcuate
recess therein, whereby the triggers are readily distinguishable
from one another by the operator, means responsive to engagement of
the "open" trigger for moving the collet means into its open
position, thereby to facilitate the insertion of a tool element
therein, and means responsive to the subsequent engagement of the
"drive" trigger for moving the collet means into its closed
position, thereby retaining the tool element therein.
Description
BACKGROUND OF THE INVENTION
In the prior art, of which I am aware, portable electric drills and
other power tools traditionally employ a chuck or collet to
securely retain the drill bit or other tool element therein and
facilitate its advancement into the workpiece. In portable electric
drills intended for consumer usage, a geared chuck and conventional
chuck key are employed. For drills intended for heavy-duty
industrial applications, the chuck may be of the conventional
geared type or else of the keyless type. In both cases, the chucks
are operated manually.
Manually-operated chucks and collets have also been used to hold
various tools and workpieces in the machine arts. One example is
the cam-operated chuck disclosed in U.S. Pat. No. 2,735,687. In
that patent, a plurality of balls cooperate with a cam formed on
the collet, and the collet opens or closes in response to the
direction in which a hand wheel is turned.
Besides the manually-operated chucks, the prior art has also
resorted to air-operated chucks for lathes and other machine tools.
This general concept has also been applied to a portable pneumatic
tool as disclosed in U.S. Pat. No. 3,712,386. In that patent, the
pressure of the compressed air selectively operates a reciprocatory
spring-loaded piston to open the gripping jaws of the tool collet,
thereby providing a quick-release feature. Alternately, as
disclosed in U.S. Pat. No. 3,724,563, the pivoted lever for
throttle control of a portable pneumatic tool is moved in a
direction opposite to its normal mode of operation to actuate a
mechanical linkage to open the tool collet.
In drills used for surgical or orthopedic purposes, a cannulated
spindle has a through bore for receiving a Kirchner pin, usually
referred to in the art as a "K wire". The K-wire is retained in a
collet or chuck mounted on the forward end of the spindle. In some
commercial embodiments, a pivoted release lever facilitates
insertion of the K-wire (and its subsequent advancement relative to
the drill) without the use of additional keys and accessories. The
lever has a bifurcated portion engaging a spring-loaded slidable
collar that actuates a mechanism to open the chuck. The remaining
portion of the lever is bent around the trigger, forwardly thereof
and providing a guard therefor, and terminates in a depending
portion. One finger on the doctor's hand engages the trigger, while
the doctor's remaining fingers are wrapped around the depending
portion of the lever during operation of the tool. This is somewhat
awkward and inconvenient. Moreover, in order to preclude
inadvertent release of the collet during a surgical procedure, the
spring pressure must of necessity be relatively heavy. As a result,
whenever release of the collet is desired, a strong force must be
exerted on the lever by the doctor. Repeated opening and closing of
the collet can thus be tiresome during an extended surgical
procedure.
In another commercial embodiment, a surgical tool is equipped with
a pneumatic collet controlled by a trigger projecting forwardly of
the pistol-grip handle of the tool. When the trigger is depressed
partially, the collet closes; to securely retain the K-wire
therein; and when the trigger is depressed fully, the tool is
energized to drive the wire. While facilitating insertion and
removal of the K-wire from the collet, the operator must
continually depress the trigger by a predetermined amount to
maintain the collet closed and to preclude inadvertent release of
the K-wire. This detracts from the doctor's concentration and
interferes with close surgical procedures in an operating room or
clinic. Moreover, if the trigger would be completely released and
the tool subsequently tilted or inverted, the K-wire could fall out
of the tool and would no longer be usable because of hygienic
considerations.
A possible solution is the surgical drill disclosed in U.S. Pat.
No. 3,718,340. In that patent, a pivoted lever is mounted on the
side of the drill. Actuation of the lever initiates a mechanical
linkage to ultimately open the gripping jaws of the collet to
release the K-wire. However, not only does actuation of the lever
require a partial release of the doctor's hand grip, but of
necessity, the drill is oriented for "right handed" usage.
Moreover, a heavy spring pressure is required to maintain the
collet in its closed position and preclude inadvertent release of
the K-wire. To overcome this heavy spring pressure, the lever
actuates the collet through a mechanical linkage. This mechanical
linkage includes a pivoted yoke, a spring-loaded slide, a plurality
of cam levers, respective push rods, and a hollow cone to actuate
the gripping jaws of the collet. This linkage is unduly
complicated, hence expensive and potentially unreliable.
Thus, the collets and chucks for surgical drills and other power
tools, resorted to in the prior art, have had certain inherent
disadvantages or deficiencies; and despite the highly-deveLoped
state of the art, a practical, economical and reliable solution to
a problem of long standing has heretofore eluded the designers and
researchers in the field.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
quick-release collet for a power tool that alleviates the
disadvantages and deficiencies of the prior art.
It is another object of the present invention to provide for use in
a power tool, such as a surgical drill, a quick-release collet
means which is simple and reliable in its operation, economical to
produce, and convenient to use.
It is yet another object of the present invention to provide a
collet means which closes in the forward direction of spindle
rotation corresponding to the drilling mode of operation of the
tool, remains closed as long as the spindle rotates (or is poised
to rotate) in its forward direction, and opens upon reverse
rotation of the spindle.
It is yet still another object of the present invention to provide
a collet that is biased to a closed position and remains closed as
the spindle rotates (or is poised to rotate) in its forward
direction, and wherein a cam-actuated mechanism overcomes the
resilient means to open the collet upon driving the spindle in its
reverse direction.
It is a further object of the present invention to provide a cam
means for opening the collet in response to reverse rotation of the
spindle, wherein the cam means functions as an overrunning clutch
during forward rotation of the spindle and as a slip clutch during
reverse rotation.
It is a still further object of the present invention to provide a
cam means having a cam track whose helix angle is less than 7
degrees.
It is a yet still further object of the present invention to
provide a ball engaging the cam track, wherein the cam track
terminates on its high side in a flat ledge for positioning the
ball thereon upon reverse rotation of the spindle to open the
collet.
It is again an object of the present invention to provide a
surgical drill having a cannulated spindle for receiving a K-wire,
wherein the K-wire is received within a collet that is opened upon
engagement of an "open" trigger and conversely, is closed upon
engagement of a "drive" trigger, the triggers being mounted
forwardly of the pistol-grip handle for the tool.
It is again another object of the present invention to provide a
cordless surgical drill having a reversible electric motor, wherein
engagement of the "open" trigger reverses the direction of rotation
of the motor and opens the collet to release the K-wire, wherein
engagement of the "drive" trigger energizes the motor in its normal
direction of rotation and closes the collet to retain the K-wire
therein, and wherein the K-wire is retained within the drill even
though the "drive" trigger is not depressed continuously.
It is again a further object of the present invention to provide a
pair of triggers on the pistol-grip handle of a surgical drill, the
triggers being disposed adjacent to each other, and the triggers
being human engineered for immediate distinction from each other,
thereby facilitating a convenient one-hand operation of the
surgical drill without requiring the doctor to look at the
triggers, and without requiring a repositioning or loosening of the
doctor's hand on the pistol-grip handle.
In accordance with the broad teachings of the present invention, a
tool has a housing with a spindle journaled therein for rotation in
forward and reverse directions, respectively. A collet means is
provided for retaining a tool element driven by the spindle. The
collet has an open position and a closed position, respectively.
Frictional means constantly urges the collet means in its closed
position, and the collet means remains closed in the forward
direction of rotation of the spindle corresponding to the driving
mode of operation of the tool. A cam means is provided, responsive
to rotation of the spindle in the reverse direction, to move the
collet means from its closed position into its open position
against the force of the frictional means.
One embodiment of the teachings of the present invention comprises
a surgical drill having a cannulated driving spindle provided with
a longitudinal through bore for receiving a K-wire or the like. A
nose housing encloses the spindle and has an internally-tapered
forward portion and a cylindrical rearward portion. A slotted
collet is driven by the spindle and has an externally-tapered
portion projecting forwardly of the spindle and seated within the
complementary internally-tapered forward portion of the nose
housing. The collet has an open position and a closed position. A
shoulder member is mounted on the spindle; and a cam is freely
mounted on the spindle rearwardly of the shoulder member, and is
secured to the rearward cylindrical portion of the nose housing. A
stationary thrust ring is retained in the housing rearwardly of the
cam. The rearward portion of the cam is formed with a cam track,
and a ball (or equivalent cam follower) is disposed between the cam
track and the thrust ring. A compression spring (or other suitable
resillient means) is disposed between the cam and the shoulder
member, constantly urging the cam and hence the nose housing in a
direction rearwardly of the spindle, and thereby closing the collet
and securing the K-wire therein. The ball has a loose engagement in
the cam track in one direction of rotation of the spindle,
corresponding to the drive position of the tool. However, in the
opposite direction of spindle rotation, (obtained by reversal of
the motor) the cam track engages the ball to move the cam and hence
the nose housing axially along the spindle and forwardly of the
drill, and against the force of the spring, thereby separating the
complementary tapered portions of the collet and nose housing,
respectively, and thereby opening the collet to facilitate release
of the K-wire therefrom.
These and other objects of the present invention will become
apparent from a reading of the following specification, taken in
conjunction with the enclosed drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of a surgical drill, wherein a preferred
embodiment of the present invention may find particular
utility;
FIG. 2 is an enlarged fragmentary portion of FIG. 1, showing the
"open" trigger for releasing the collet, and further showing the
"drive" trigger for closing the collet and energizing the tool;
FIG. 3 is a partial longitudinal section view of the forward
portion of the drill of FIG. 1, drawn to an enlarged scale, and
showing a preferred embodiment of the collet means of the present
invention, the collet means being shown in its closed position;
FIG. 4 is a section view, taken along the lines 4--4 of FIG. 3,
showing the K-wire retained in a slotted collet member of the
collet means;
FIG. 5 is a stepped section view, taken along the lines 5--5 of
FIG. 3, showing (in plan view) the cam track formed in the rearward
portion of the cam;
FIG. 6 is a rear perspective view of the cam;
FIG. 7 is a longitudinal section, corresponding to a portion of
FIG. 3, but showing the cam and nose housing moved forwardly of the
spindle, thereby allowing the collet to move into its open
position;
FIG. 8 is a view showing the thrust ring, ball and cam in
elevation, the view corresponding to the closed position of the
collet;
FIG. 9 corresponds to FIG. 8, but showing the cam track engaging
the ball to move the cam forwardly of the spindle, the view
corresponding to the open position of the collet;
FIG. 10 is a plan layout of the cam track, the ball being shown (in
broken lines) in a position corresponding to the open portion of
the collet;
FIGS. 11-15 are schematic sequence views, showing the advantages in
using the preferred embodiment of the present invention;
FIG. 16 is an enlarged elevation of the preferred embodiment, with
parts broken away and sectioned; and
FIGS. 17-19 are side elevations of additional tools in which the
teachings of the present invention may be applied.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to FIGS. 1 and 2, there is illustrated a surgical
drill 10 with which the teachings of the present invention may find
particular utility. It will be understood by those skilled in the
art, however, that the surgical drill 10 constitutes only one
embodiment of the present invention, and that the teachings of the
present invention are equally applicable to a wide variety of tools
and devices. With this in mind, the drill 10 is adapted to drive a
Kirschner pin 11 (referred to in the art as a "K-wire") and
comprises a motor housing 12, a gear housing 13 forwardly thereof,
a nose housing 14 through which the K-wire projects, a depending
pistol-grip handle 15, and a pair of triggers projecting forwardly
of the pistol-grip handle, one comprising an "open" trigger 16 for
opening the collet means and facilitating release of the K-wire,
and other comprising a "drive" trigger 17 for closing the collet
means and securing the K-wire therein, as hereinafter described in
detail. Preferably the drill is cordless and has a removable
battery pack 18 constituting part of the pistol-grip handle.
With reference to FIGS. 3 through 6, a driving output spindle 19 is
journaled in bearings in the housing (as hereinafter described).
The spindle is cannulated and has a longitudinal through bore 19a
for receiving the K-wire 11. The K-wire is retained with respect to
the spindle by the collet means 20 of the present invention. Ihis
collet means comprises a collet member 21 having a forward portion
22 and a rearward portion 23. The forward portion has a plurality
of slots 24 (as shown more clearly in FIG. 4) and further has an
annular externally-tapered portion 25 seated within a complementary
internally tapered annular portion 26 of the nose housing.
Preferably, the collet also has a reverse annular tapered surface
25a seated against a complementary annular tapered surface 19b on
the spindle, thereby further maintaining concentricities. The
rearward portion of the collet member is cylindrical and is
received within the bore in the spindle. Preferably, but not
necessarily, the collet is coupled to the spindle by means of a
transverse pin 27 received (with axial clearance) within a
transverse hole 28 in the spindle. A split keying ring 29 has an
inwardly-extending annular portion received within an external
annular groove 30 formed on the spindle. A stepped shoulder member
31 is slidably fitted over the spindle and is held against the
split keying ring.
A cam 32 is freely mounted concentrically about the spindle and has
a threaded connection 33 with the rearward cylindrical portion 34
of the nose housing. The cam and nose housing thereby form an
integral subassembly and are free to move axially with respect to
the spindle. Preferably, but not necessarily, a pair of thrust
washers 35 and 36 are positioned forwardly of the cam. A
compression spring 37 (or other suitable resilient means) is
positioned concentrically about the spindle and is seated between
the washers and the stepped shoulder member. The spring constantly
urges the cam and hence the nose housing rearwardly of the spindle,
thereby firmly seating the slotted tapered forward portion of the
collet member within the internally-tapered forward portion of the
nose housing, and thereby maintaining the collet in a closed
position and securely retaining the K-wire therein.
A cam track 38 is formed on the rearward portion of the cam, and a
stationary thrust ring 39 is retained within the housing. The
thrust ring has a radial clearance with respect to the rotating
spindle and is held in its stationary position by the frictional
force exerted by an O-ring 40 which maintains the ring next to the
inner race of the ball bearing 41. A cam follower is disposed
between the thrust ring and the cam track formed on the cam.
Preferably, the cam follower comprises a ball 42 (or other suitable
anti-friction element) whose thrust surface is provided by the
thrust ring.
With reference again to FIGS. 3 through 6, and with further
reference to FIGS. 7 through 9, as long as the spindle 19 is
rotating (or is positioned to rotate) in the direction of the arrow
in FIG. 8, that is, clockwise as viewed from the rear of the
spindle and looking forwardly of the drill, the collet 21 will
remain in its closed position to securely retain the K-wire
therein. In this position, the ball 42 has an axial clearance with
respect to the cam 32 and thrust ring 39 (as shown in FIGS. 3 and
8) and for all intents and purposes, is inoperative relative to the
cam track 38. However, when the direction of rotation of the
spindle 19 is reversed, as indicated by the arrow in FIG. 9, (that
is, counterclockwise as viewed from the rear of the spindle and
looking forwardly of the drill) the cam track 38 engages the ball
42 and rides around the ball, as the ball moves relatively up the
track, thereby moving the cam forwardly and axially along the
spindle (as indicated by the large arrow 43 in FIG. 9). This cam
action is against the frictional bias forces provided by the spring
37. Since the nose housing 14 is secured to the cam, the nose
housing also moves forwardly, thereby separating the tapered
portions 25 and 26 on the collet member and nose housing,
respectively, and thereby opening the slotted collet member 21 to
facilitate the withdrawal of the K-wire 11 therefrom. Nor must
power always be used to open the collet. If desired, the collet may
be opened manually by simply turning the nose housing,
counterclockwise, about one-and-a-half turns.
Although the cam 32 is freely mounted relative to the spindle,
there is inherent friction in the system created by the spring 37.
This friction operates through the collet and nose housing to
rotate the cam upon reverse rotation of the spindle. The ramp of
the cam track 38 is on the moving surface (the cam 32) and acts as
a wedge to engage the ball 42 which, being stationary, has inertia.
The cam track moves around the ball to move the cam forwardly. If
the cam were not formed on the surface of the moving member, the
mechanism might not engage the cam follower and might possibly
malfunction. With the disclosed structure, however, the cam always
functions to open the collet, regardless of the position or
orientation of the tool.
With reference to FIG. 10, the cam track has a ramp or helix angle
A which is preferably less than 7 degrees. This assures that the
relative movement between the ball and the cam track will be
substantially smooth and uniform, and that the ball will not "shoot
out" in its relative movement with respect to the rotating cam
track. Moreover, the high point of the cam track terminates in a
flat ledge 44 that serves to "park" the ball and preclude its
relative movement back down the cam track.
Thus, it will be appreciated by those skilled in the art that the
cam means functions on an overrunning clutch in the forward
rotation of the spindle; and in the reverse direction, the cam
means functions as a slip clutch, thereby precluding damage to the
motor or undue drainage of the battery pack in the event the "open"
trigger is not released and the motor is thus continually operated
in the reverse direction.
With reference to FIGS. 11 through 15, the special advantages of
the present invention (as applied to the surgical drill 10) will be
appreciated. In FIG. 11, the "open" trigger 16 has been depressed
to move the collet to its open position and facilitate insertion of
the K-wire 11 into the drill. The drill is so designed as to enable
the K-wire to be inserted from either the front or the back of the
drill. The K-wire is manually advanced forwardly of the drill (to
the desired amount) and the "drive" trigger is depressed to close
the collet and hold the K-wire securely within the drill, as shown
in FIG. 12. Thereafter, the K-wire will be held securely within the
drill, even through the "drive" trigger is released. It is not
necessary to continually depress the "drive" trigger, and the
K-wire is retained until the "open" trigger is again depressed.
This is an important feature of the present invention. Thus, as
illustrated in FIG. 13, the doctor's (or operator's) hand need not
be held on the drill, and indeed the drill can be inverted or
tilted, without fear of having the K-wire fall out of the unit.
This is especially important in surgical procedures in operating
rooms, or orthopedic procedures in clinics, where hygienic
cleanliness is mandatory. Thereafter, as shown in FIG. 14, the
"drive" trigger is again depressed, driving the K-wire and
advancing it into the bone 45 of the patient. To retract the drill
rearwardly of the K-wire (to facilitate subsequent advance of the
K-wire into the bone) the "open" trigger is depressed to open the
collet. A portion of the K-wire is retained in the bone, and the
drill is slidably moved along the K-wire to expose the desired
additional length of K-wire to be inserted into the patient's bone.
Thereafter, the "drive" trigger is again depressed and the cycle is
repeated. When the desired length of K-wire has been fully
positioned in the bone, the excess may be snipped off by suitable
means.
During the surgical or orthopedic procedure (illustrated
schematically in FIGS. 11-15) the doctor's hand may be held in the
same position. This position need not be loosened or relocated
relative to the pistol grip handle, nor is the doctor required to
look at the triggers. The "open" and "drive" triggers, which are
disposed adjacent to each other, are human engineered and readily
distinguishable from one another. More specifically, the "drive"
trigger 17 is larger than the "open" trigger 16 and has a forward
face provided with an arcuate recess 17a formed therein (as shown
in FIG. 2). Thus, the doctor may readily acquire a steady
comfortable grip for immediate one-hand control without being
distracted away from the delicate operation or procedure being
performed. This is a salient advantage of the present invention
over the prior art. Moreover, the drill may be used for either
left-handed or right-handed operation.
Preferably, the drill is lightweight and powerful and is of the
cordless type, thus eliminating the necessity for cords or hoses to
power the drill. Thus, as shown in FIG. 16, the cannulated spindle
is journaled fore and aft in the ball bearing 41 (previously noted)
and a sleeve bearing 46, respectively. These bearings are suitably
retained within a frame 47. Preferably, the motor housing and gear
housing are formed as "clamshell" plastic members joined together
along a common longitudinal midplane (not shown) and suitably
secured to the frame. A ring 48 is threaded into the frame, as at
49, and retains the ball radially. Preferably, the ring carries
sealing members 50 and 51. A gear 52 is press-fitted on the spindle
and meshes with an intermediate gear 53 mounted on a stub shaft 54
retained within the frame. The gear 53 is formed as a cluster with
a gear 55 which engages the pinion 56 of the armature shaft 57 of
the motor 58. The motor is suitably mounted on the frame and is
preferably of the high-efficiency permanent magnet type. The motor
is reversible and is driven by the replaceable battery pack 18. The
electrical connections between the motor and battery are omitted
herewith for ease of illustration. The construction of the battery
pack, motor and gearing (and their cooperation with each other)
form no part of the present invention, but are shown herein to
complete the disclosure.
With further reference to FIG. 16, the motor is controlled by a
reversing switch 59 having a pivoted toggle memter 60. This toggle
member is selectively engaged by the triggers 16 and 17,
respectively. Each of the triggers is provided with a substantially
identical mechanism to cooperate with the switch toggle; hence the
mechanism will be described with reference only to "drive" trigger
17. Each trigger has a central boss 61 formed with a blind axial
bore 62 for receiving the knurled portion 63 of a steel pin 64;
preferably the trigger is molded integrally to the pin. The pin is
slidably received within a bore 65 formed in the housing, and a
seal 66 may be carried on the pin. A compression spring 67 is
seated between the housing and the trigger and constantly urges the
trigger forwardly of the housing. When the trigger is slidably
depressed or retracted within the housing, the pin engages a pocket
68 on the pivoted switch toggle, thereby closing the switch and
energizing the motor (which is reversible). The "drive" trigger 17
energizes the motor in its forward direction, and the "open"
trigger 16 energizes the motor in its reverse direction (as
previously noted). The surgical drill is completely sealed and may
be suitably sterilized; however, the sealing means forms no part of
the present invention, nor should the invention be limited
thereby.
Indeed, as previously noted, the teachings of the present invention
are broader than the surgical drill disclosed herein and are
applicable to a wide variety of tools and devices. Examples are the
portable pneumatic tool 69 of FIG. 17; the portable hobbyist tool
70 of FIG. 18, powered by a flexible cable 71; and the
hand-operated drill 72 shown in FIG. 19. Each of these products has
a spindle capable of forward and reverse operation.
Obviously, many modifications may be made without departing from
the basic spirit of the present invention. Accordingly, it will be
appreciated by those skilled in the art that within the scope of
the appended claims, the invention may be practiced other than has
been specifically described herein.
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